潜热型低熔点液态金属功能热流体的制备及热物理特性研究

Study on Preparation and Thermal Physical Performance of Latent Functionally Thermal Fluid Using Liquid Metal with Low Melting Point as Carrying Fluid

为获得具有高效传热能力的散热工质,结合液态金属导热系数高,潜热型功能热流体表观比热大的优点,对正二十烷-蜜胺树脂微胶囊表面进行化学镀铜改性,再掺入低熔点液态镓中进行机械搅拌和超声振动,形成均匀稳定的相变微胶囊(Microencapsulated phase change material,MEPCM)-低熔点液态金属(Liquid metal,LM)悬浮液并进行形貌表征和热物理特性测试。结果表明,镀铜MEPCM的铜镀层包覆均匀,无Cu2O存在;镀铜MEPCM以及MEPCM悬浮液的相变区间相对于MEPCM未发生变化;悬浮液的潜热随微胶囊体积分数的增加而增大,体积分数为20%时悬浮液的表观比热可达单相镓的3.03倍,导热系数为单相镓的73%;悬浮液黏度随体积分数的增加而增大,随温度的升高而降低,体积分数小于20%时MEPCM-LM悬浮液仍可被近似看作是均匀的牛顿流体。

The two merits of high thermal conductivity of liquid metal （LM） and big apparent specific heat of latent functionally thermal fluid can be integrated to acquire the coolant with better heat transfer ability. The microencapsulated Eicosane with melamine-formaldehyde shell is mixed into liquid Gallium after surface character of microencapsulated particles had been changed by electroless copper plating. Then, the even and steady microencapsulated phase change material （MEPCM） suspension using liquid metal with low melting point as carrying fluid can be gained by being mixed round mechanically and being librated ultrasonically. The appearance of MEPCM with Cu plating layer is characterized and the thermal physical properties of suspension are tested. The results show that the Cu plating layer on MEPCM particle is smooth and even, and there is no Cu20 existing in plating layer; the phase change temperature ranges of MEPCM with Cu plating layer and MEPCM suspension are same to that of MEPCM; The latent of suspension increases with increasing volume concentration of MEPCM, the apparent specific heat is up to 3.03 times of that of pure Gallium and the thermal heat conductivity is 73% of that of Gallium for Ф= 20% suspension; the viscosity of suspension increases with increasing volume concentration and decreases with increasing temperature, the MEPCM-LM suspension with Ф〈 20% can be considered approximately as even Newton fluid.